FRIDAY, Feb. 13, 2015 (HealthDay News) -- Smoking may damage part of the brain by causing thinning in a crucial area, new research shows.

The study included more than 500 male and female smokers, former smokers and nonsmokers who were an average of 73 years old.

Brain scans revealed that current and former smokers had a thinner cortex than those who never smoked. The cortex is where important thought processes such as memory, language and perception occur.

The researchers also found that stopping smoking leads to partial restoration of the cortex's thickness, but the process is slow and incomplete. Heavy ex-smokers who hadn't smoked for more than 25 years still had a thinner cortex than nonsmokers, the researchers found.

The cortex grows thinner with age, but smoking appears to speed that thinning. And, a thinner cortex is associated with mental decline, the researchers noted.

The study was published online Feb. 10 in the journal Molecular Psychiatry.

"Smokers should be informed that cigarettes could hasten the thinning of the brain's cortex, which could lead to [problems with thinking and memory]. Cortical thinning seems to persist for many years after someone stops smoking," lead author Dr. Sherif Karama, an assistant professor of psychiatry at McGill University in Montreal, said in a university news release.

SOURCE: McGill University, news release, Feb. 10, 2015